1. Field of the Invention
The present invention relates to a printing apparatus that carries out printing by interpreting a page description language of print data sent from a host apparatus.
2. Description of the Related Art
Conventionally, a printer apparatus as a printing apparatus that carries out printing by interpreting a page description language of print data sent from a host apparatus is connected on a network and prints print data sent from a plurality of host apparatuses. When printing a confidential document, etc. (hereinafter referred to as “secret printing”) using such a printer apparatus, a technique is known which prevents printing unless a password is entered from a panel provided on the printer apparatus even if a host apparatus instructs that print data should be printed.
On the other hand, print data sent from a host apparatus to this type of printer apparatus is normally written in a page description language (hereinafter referred to as “PDL data”) such as PCL of Hewlett-Packard Company and PostScript of Adobe Systems Inc.
The printer apparatus described above temporarily stores print data sent from the host apparatus in memory of the printer apparatus and waits for a password to be entered before printing the data, and therefore the printer apparatus needs to incorporate memory that can temporarily store the print data. At this time, the print data sent from the host apparatus is written in PDL data. The print data written in this PDL data has a structure with a plurality of layers and the volume of the print data in this case is not predictable from the number of pages, etc. of the print data. Thus, this type of printer apparatus has a problem of requiring bulk memory anticipating a case where large-volume print data is required.
For such memory, a hard disk, etc. is normally used. With bulk memory such as a hard disk, this printer apparatus can perform secret printing. Due to the necessity of bulk memory such as a hard disk, this type of printer apparatus has another problem of increasing the cost of apparatus.
Such problems can also occur in cases other than secret printing. For example, these problems may also occur when a plurality of print data pieces is sent from host apparatuses on a network simultaneously and part or the whole of such print data should be temporarily stored in memory in the printer apparatus.